This invention relates generally to shoes, and more particularly to shoes having an upper for supporting the ankle of a user and storing energy when the upper is moved toward the dorsiflexion position.
During athletic endeavors involving jumping and quick movement, such as running, basketball, tennis, etc., a participant's ankles are often subjected to substantial shock The participant must contract certain muscles around the ankle to initiate the jump and then relax those muscles and contract different muscles to counteract the impact of landing The jumping and landing cause the participant to expend much energy, thereby fatiguing the muscles Also, when the participant lands on one foot after jumping, the impact on the ankle may be several times greater than the weight of the participant Such impact often results in ankle injuries.
Most athletic shoes have cushioned soles to absorb some of the shock during impact. The cushioned sole absorbs some of the shock by converting some of the kinetic energy, i.e , the energy of motion, of the user wearing the shoe to heat-energy in the soles This heat-energy is not stored as potential energy to assist the user in jumping. Rather, the heat-energy is dissipated to the environment and, therefore, not useful to the user. A shoe which stores at least some of the kinetic energy as potential energy to assist the use in jumping is needed.